On Fri, Jul 26, 2013 at 3:28 PM, Tom Lane <tgl@sss.pgh.pa.us> wrote:
> Lonni J Friedman <netllama@gmail.com> writes:
>> nightly=# ALTER SERVER cuda_db10 OPTIONS (SET use_remote_estimate 'true') ;
>> ERROR: option "use_remote_estimate" not found
>
>> Am I doing something wrong, or is this a bug?
>
> [ experiments... ] You need to say ADD, not SET, to add a new option to
> the list. SET might more appropriately be spelled REPLACE, because it
> requires that the object already have a defined value for the option,
> which will be replaced.
>
> Our documentation appears not to disclose this fine point, but a look
> at the SQL-MED standard says it's operating per spec. The standard also
> says that ADD is an error if the option is already defined, which is a
> bit more defensible, but still not exactly what I'd call user-friendly.
> And the error we issue for that case is pretty misleading too:
>
> regression=# ALTER SERVER cuda_db10 OPTIONS (use_remote_estimate 'true') ;
> ALTER SERVER
> regression=# ALTER SERVER cuda_db10 OPTIONS (use_remote_estimate 'false') ;
> ERROR: option "use_remote_estimate" provided more than once
>
> I think we could do with both more documentation, and better error
> messages for these cases. In the SET-where-you-should-use-ADD case,
> perhaps
>
> ERROR: option "use_remote_estimate" has not been set
> HINT: Use ADD not SET to define an option that wasn't already set.
>
> In the ADD-where-you-should-use-SET case, perhaps
>
> ERROR: option "use_remote_estimate" is already set
> HINT: Use SET not ADD to change an option's value.
>
> The "provided more than once" wording would be appropriate if the same
> option is specified more than once in the command text, but I'm not sure
> that it's worth the trouble to detect that case.
>
> Thoughts, better wordings?
Thanks Tom, I've confirmed that using ADD was the solution. I think
your suggested updated ERROR & HINT text is an excellent improvement.
It definitely would have given me the clue I was missing earlier.